1. Field of the Invention
The present invention relates to a mixing faucet system for an aircraft disposed in lavatory units of aircrafts.
2. Description of the Related Art
Conventionally, in lavatory units of aircrafts, cold water is provided via pipes disposed in the aircraft and hot water is provided by heating the cold water using a small electric water heater disposed in the lavatory unit. A mixing faucet mixes the cold water and hot water within the lavatory unit of the aircraft so as to provide water having a desired temperature. In the recent mixing faucet for aircrafts, a control valve is provided in a discharge unit attached to the wall of the lavatory so as to control the water temperature and water quantity.
In place of mechanical faucets in which the discharge lever is operated manually to open a mechanical valve adopted in conventional mixing faucets for aircrafts, electronic faucets are being adopted in which the opening and closing of solenoid valves are controlled based on the sensed result via an infrared sensor. The latter mixing faucet arrangement responds to the psychology of the user wishing to avoid contact with the mixing faucet disposed in the lavatory unit as much as possible.
On the other hand, methods for controlling the water temperature include a manual method in which the lever directly connected to the mixing valve is operated manually and an electric method in which a motor-driven flow rate control valve is operated via a touch switch. The manual method is more popular in aircrafts since the manual system has lighter weight, simple structure and lower failure rate.
According to the manual-type temperature control system, however, the user must manually operate a lever with his or her hands to control the water temperature, which is against the psychology of the user to avoid contact with the lever. Furthermore, the water discharged during the several seconds of water temperature control is consumed vainly.
Moreover, when the aircraft is parked for a long time in a cold district, the water in the pipes of the aircraft may freeze when draining of water is not performed, so that it is preferable for the mixing faucet system to endure as much number of times of freezing as possible. Currently, however, the durability relies on the expansion of the water supply pipe and the intensity of the material used for the faucet, so that when the water is repeatedly frozen, the faucet system is subjected to mechanical fatigue and cannot endure a large number of times of freezing.
However, the mixing unit and the discharge unit of the prior art mixing faucet were integrated, so that the size of the faucet system visible to the user in the lavatory unit was large, and the faucet system was subjected to design limitations from the viewpoint of designing of wash basins and lavatory units.
Japanese Patent Application Laid-Open Publication No. 0.10-103536 (patent document 1) discloses a hot and cold water mixing-supplying system comprising a mixing faucet to which a hot water side piping through which hot water flows and a cold water side piping through which cold water flows are connected, wherein via a temperature sensor for detecting the temperature of the hot water flowing through the hot water side piping and a solenoid valve switched by detection of the temperature sensor, an instant boiler is provided on a primary portion of the hot water side piping. According to the hot and cold water mixing-supplying system, when hot water used previously remains in a cooled state in the hot water side piping, the solenoid valve is switched by the sensed temperature of the temperature sensor, so that the cooled water is supplied to the instant boiler and the hot water stored in advance in the instant boiler is output and supplied to the mixing faucet. Moreover, when the hot water formed in the hot water supplying system exceeds a desirable temperature, the solenoid valve is switched by the sensed temperature of the temperature sensor, according to which water is sent directly to the mixing faucet without passing the instant boiler and discharged through the discharge port. As described, the disclosed system enables to provide hot water mixed to a desirable temperature instantly when the mixing faucet is operated, and to provide water continuously.
In lavatory units of aircrafts, it is desirable that the discharge unit of the faucet system visible to the user is downsized. Therefore, the problem to be solved in the hot and cold water mixing faucet within lavatory units of aircrafts is to downsize the portion visible to the user as much as possible.